EXCLUSIVE: Janina Gavankar (The Gates, The L Word) has joined True Blood‘s upcoming fourth season as a regular. Additionally, Alexandra Breckenridge (Dirt, Life Unexpected) and Vedette Lim (As the World Turns) have come on board the HBO smash as recurring. Meanwhile, co-star Jessica Tuck has been promoted to a full-fledged series regular.

Gavankar will play Luna, a super-sexy public school teacher and shapeshifter who is first seen attending an informal gathering with others like her. Breckenridge, a noted voiceover artist who can regularly be heard on Fox’s Family Guy, will play Daisy, a member of a wiccan group founded by Marnie (new series regular Fiona Shaw). Finally, Main Title-repped Lim will portray Naomi, a fierce fighter who participates in underground cage matches for money.

Tuck, repped by Michael Greene and Assoc., joined True Blood as even-tempered vampire mouthpiece Nan Flannigan in season 1. Her role was beefed up considerably last season, so news of her full-time upgrade doesn’t come as a complete surprise.

The flurry of True Blood castings arrive one week before production on season 4 is scheduled to get underway. Michael Ausiello will be contributing to Deadline.com and Movieline.com as he preps for the early 2011 launch of a new TV-centric website.